1. Field of the Invention
This invention relates to the preparation of aryl carboxylates and more particularly to the preparation of aryl carboxylates from the corresponding arylmetallo carboxylate.
2. Description of the Prior Art
Aryl carboxylates, such as phenyl carboxylates (e.g., phenyl acetate, phenyl salicylate and the like) find a wide variety of uses. For example, phenyl acetate can be hydrolyzed to prepare phenol, and also finds use as a solvent. Phenyl salicylate is used as a preservative.
Various methods for preparing aryl carboxylates are known. For example, phenyl acetate can be prepared from the reaction of phenol and acetyl chloride or acetic anhydride, or by heating triphenyl phosphine in the presence of potassium acetate and alcohol. See, e.g., Condensed Chemical Dictionary, 8th Ed., p. 678 (1971). Also known is a process for preparing aryl carboxylates by reaction of aryl thallium (III) metallates with the corresponding carboxylic acid. See U.S. Patent 4,182,915 (issued in 1980 to R. J. Harvey).
Diaryl mercury compounds are known to react with aryl iodoso dihalides to produce a diaryliodonium halide and an aryl mercuric halide compound. F. M. Beringer, et al., 75 J. Amer. Chem. Soc. 2705 (1953). Also known is the reaction of phenyl magnesium chloride with phenyl iodoso dichloride to produce a complex mixture of products which has been variously reported as being only phenyl iodide and diphenyl or a mixture of phenyl chloride, phenyl iodide, diphenyl and diphenyl iodonium chloride. R. B. Sandix, 32 Chem. Rev. 249, at 261 (1943).
The use of such diaryl iodonium salts in various synthesis reactions has been reported in a number of references. In addition to the above two articles by Beringer, et al. and Sandix, illustrative literature on this subject includes F. M. Beringer, et al., 75 J. Amer. Chem. Soc. 2708 (1953); M. C. Caserio, et al., 81 J. Amer. Chem. Soc. 336 (1959); F. M. Beringer, et al., 81 J. Amer. Chem. Soc. 342 (1959); and F. M. Beringer, et al., 81 J. Amer. Chem. Soc. 351 (1959). Studies of use of diphenyl iodonium salts in hydrolysis reactions show copper (I) and copper (II) to be catalysts for the hydrolysis reaction. The non-catalyzed hydrolysis reaction is suppressed by the presence of acid. The copper catalyzed reaction was also found, in varying degrees, to be retarded by the presence of acid.
Diphenyliodonium bromide has been reacted with sodium benzoate to form phenyl benzoate and phenyl iodide, and the reaction has been found to be faster in strong bases. F. M. Beringer, et al., 75 J. Amer. Chem. Soc. 2708 (1963).